Various fields such as, for example, biotechnology, semiconductor, pharmaceutical, food processing, and medical, require fluid handling systems that are clean and sterile while at the same time having increased cycle life and operating pressure. A very important consideration is ease with which the fluid handling components can be cleaned. The ease with which a system can be cleaned depends on, among other things, minimal dead volumes and entrapment areas. The fluid handling system must also use components that are inert to the fluid. Such systems often use valves as flow control devices, and diaphragm valves in particular are often used.
U.S. Pat. No. 5,549,134 (the ““134 patent” hereinafter), the entire disclosure of which is fully incorporated herein by reference, describes a diaphragm valve design that is particularly well suited for these various sanitary applications. The present invention is directed to various improvements and additional features in the design of the “134 patent valve to enhance its cleanability and operating performance including, among other things, its operating pressure characteristic and cycle life. Still further the present invention is directed to increasing the flow rate.
Another important aspect of valves that are used in clean environments is the sealing of the fluid within the valve and thereby preventing contamination of surrounding environment. Many valves, including radial diaphragm valves, incorporate a flexure member, which acts as a barrier between the process fluid and the external environment. This member forms a peripheral seal around the fluid portion of the valve cavity while allowing the center seat portion to flex to seal off the fluid entrance. For valves that are used in connection with highly corrosive chemicals, the flexure member is made from an inert substance, such as PFA or PTFE. However, due to the nature of these substances and the relatively thin flexure sections they form, many corrosive fluids are capable of permeating the flexure section to the surrounding environment. In order to keep the corrosive fluids from permeating the flexure section, the thickness of the flexure section can be increased. However, the increase in the thickness of the flexure member subjects the flexure member to higher stress levels, which frequently cause early failure of the diaphragm web. As such, there exists a need for a diaphragm that is chemically resistant and provides a quality seal around the fluid passageway, wherein the diaphragm further minimizes permeation of corrosive chemicals, yet maintains a high degree of flexure.